I sold my apartment on February 2, but I've just received the property tax notice. Do I have to pay it, or can I ask the buyer to pay part of it?

In principle, property tax is due by the owner on January 1 of the current year. As a result, in principle, you are liable for it.

However, it is customary to specify in the deed of sale that the seller and buyer will share the burden of this tax on a prorata temporis basis, i.e. according to the date of transfer of ownership.